1. Field of the Invention
This invention relates to an improved head shell for pick-up arms and a method of making same.
2. Discussion of the Prior Art
Conventionally, as shown in FIG. 1, head shells comprise a horizontal part 1 for mounting a cartridge and a vertical part 2 formed at the back end of horizontal part 1 for mounting a connector 3. Connector 3 is affixed onto vertical part 2 by means of caulking, screwing, or adhesion. The cross-sectional forms of horizontal part 1 are roughly as shown in FIGS. 2(A), 2(B) and 2(C). As for the material and forming methods, the head shells are made of light alloys of aluminum, magnesium, ceramic, etc. by means of forging, die casting, or plastic molding.
In general, the required characteristics for this type of head shells are lightness, adequate bending and torsional strengths, large dampening factor, etc. In the case of conventional head shells, the lightness requirement is more or less satisfied; however, the bending and torsional strengths have been inadequate. Consequently, as shown at r in the frequency response graph of FIG. 3, partial resonance occurs resulting in an inferior sound quality. This is attributable to the inadequate strength of the head shell in view of the connector 3.